1. Field of the Invention
This invention relates generally to firearms and guns such as rifles and to the bullets propelled therefrom, and in particular relates to a firearm having a rectangular barrel for shooting a disk-shaped bullet and to a disk-shaped bullet and cartridge for use with the firearm. The barrel has a non-smooth high friction interior barrel teething surface.
2. Description of the Related Art
There are many different types of firearms used for sporting, military or other activities, primarily having in common that a projectile (e.g., a bullet or ball) is propelled by some means away from the firearm through a barrel. Propulsion upon discharge of the firearm is accomplished by means such as gunpowder alone, a percussion cap plus gunpowder or a cartridge containing primer (impact sensitive chemical mixture), gunpowder and bullet. Ignition of the gunpowder, usually within the cartridge casing, causes a sudden formation of gas which propels the projectile out the barrel.
Early firearms used simple, spherical balls as bullets, typically made of lead and having diameters sized to fit closely in the cylindrical barrels of the firearms. In the early 1800's pointed bullets having a conical front end were developed. Typically they had a hollow rear end with some structural component designed to grip and engage rifling within the barrel. Whatever the structure, it is important that bullets are manufactured without problematic surface imperfections and that they form a seal with the bore of the firearm so that gas does not leak past the bullet, reducing the efficiency of the firearm. The bullet must also engage rifling within the firearm barrel without damaging or fouling the bore of the firearm and without distorting the bullet.
Most firearms designed to discharge a single projectile at a time typically have a bullet guide feature known as “rifling”. The process of rifling provides lands with interleaved helical (“spiral”) grooves within the barrel of a round-bored firearm, generally with two or more grooves cut or milled throughout the length of the barrel. The diameter of the projectile or bullet that is fired through the barrel corresponds with the groove diameter. The rifling causes the projectile to spin and become gyroscopically stabilized. The projectile is then aerodynamically stabilized and has increased accuracy. The “twist rate” of rifling defines the distance the projectile moves within the barrel to complete one full revolution. The shorter the distance, the greater (faster) the twist rate, so that the projectile is rated at a faster spin rate. For spherical lead balls, only a low twist rate (e.g., 1 turn in 48 inches) is used, while barrels used with long narrow bullets have faster twist rates (e.g., 1 turn in 8 inches). The twist rate may increase within the barrel. Generally, firearm barrels have rifling that provides a twist rate to stabilize the type of projectile for which the firearm is typically used. An alternative bullet guide feature is provided by the patent of Hagan (U.S. Pat. No. 3,777,385) and comprises a plurality of adjacent aperture disc assemblies fitted within the cylindrical barrel.
Rifle cartridges are designed to work with particular interior bore dimensions of the gun chamber. A cartridge holds the bullet, propellant and primer, usually within a case (e.g., of metal) that fits precisely within the firing chamber of a firearm.
The objects of the invention of the parent application herein (Ser. No. 13/666,322 filed Nov. 1, 2012) include to provide a firearm, bullet case and bullet providing increased stability when the firearm is fired, to provide a firearm having a barrel with a rectangular bore and a bullet case and disk-shaped bullets for use with the firearm, to provide a disk-shaped bullet that is compact and thin for high capacity storage and magazine loading, and to provide a bullet that has greater penetration, similar to a rotating circular blade, with greater surface edge.
It has been found that providing a high friction surface on the firearm interior barrel teething surface improves firing efficiency of the firearm of the prior invention.
It is therefore an object of the invention herein to provide an improved barrel teething surface for the firearm invention disclosed and claimed in the above-referenced parent application of the instant patent application.
Other objects and features of the inventions will be more fully apparent from the following disclosure and appended claims.